Fender system for underwater drilling platforms



c. P, BESSE 2,915,879

FENDER SYSTEM FOR UNDERWATER DRILLING PLATFORMS Dec. 8, 19521 Filed May 9. 1955 INVENTOR CELES/E PAUL BESSE ment' andoperating personnel to United States Patent C FENDER SYSTEM FOR UNDERWATER DRILLING PLATFORMS Celestine Paul Besse, New Orleans, La., assignor to Californa Research Corporation, San Francisco, Calif., a corporation of Delaware Application May 9, 1955, Serial No. '506,881 1 Claim. (Cl. 61--48) This invention relates to offshore drilling platforms, more particularly to apparatus for protecting the supporting columns for an offshore drilling platform from impact by surface vessels and has for an object the provision of a fender system for protecting the supporting columns of an underwater work platform which includes a plurality of vertically disposed cables laterally spaced around the periphery of the platform for supporting fender means which extend transversely around the periphery of the platform in the vicinity of the water line on the supporting columns. Means for placing said cables under tension to a predeterminable extent are provided to permit said fender means and said cables to absorb the impact of a surface vessel and prevent damage to the supporting columns of the platform.

AIn the drilling of oil wells, and the like, at an underwater or offshore location, it is common practice to support the drilling or work platform on a mobile foundation, such as a barge, which may be iioated to location, then lowered into engagement with the underwater bottom. The platform remains abov'ewater level due to its support upon a plurality of columns extending between the foundation barge and the drilling platform. In such structures it is desirable and frequently necessary to supply drilling equipthe platform at regular intervals by surface vessels which come alongside of the drilling structure. Each approach of a surface vessel of course entails a possibility of impact and damage to the lcolumns supporting the work platform above the water level. In some cases, these supporting columns form hydraulic cylinders through which pistons operate to extend andretract stabilizing pontoons useful in submerging or raising the barge for movement to and from the drilling location. Such impact to the columns may thus require repair or replacement thereof in open water, and the damage may even besuch as to endanger the drilling operation. Accordingly, it is important that the support columns be adequately protected from damage by surface vessels.

While particular care is taken by the servicing vessels to prevent impact with the stationary drilling platform, under conditions of low visibility or storms, it may be necessary to service the drilling platform, for example, to evacuate personnel therefrom. Thus, such precautions are not alwayssuflicient to avoid impact damage to the supporting columns.

In other types of offshore drilling structures, protection Of ,the Supporting columns is also important where the drillingQplatform is supported by a few columns whose lowery ends directly engage bottom. In such installations, the columns not only support the platform but also are used in the jacking operation wherein the working platform moves from a floating position into an elevated position through operation of jacks which permit the platform to climb the columns. Thus, the mobility of the entire structure, representing a capital investment in the range of over one million dollars, may be seriously affected if im- 2,915,879 Patented Dec. 8, 1959 Y'ice pact 1s permitted between surface vessels servicing the platform and the supporting columns.

In accordance with the preferred embodiment of the present invention, the danger of impact to the supporting columns of an offshore drilling structure is, to a great extent, alleviated by a provision of a plurality of vertical cables extending from substantially the working platform downwardly to a support means, such as the submerged barge, with a plurality of fender means extending transversely about the periphery of the drilling platform in at least the area serviced by surface vessels, said cables and said fender means being laterally displaced from the support columns for the purpose of absorbing through the vertically disposed cables the impact of surface vessels approaching the drilling structure. l

In a preferred form of apparatus for carrying out the invention, the horizontally spaced and vertically disposed cables are pivotally connected at their lower ends to the submerged barge and pass upwardly to a clamping arrangement which permits a predetermined tension to be placed upon the cables. Further, said fender means supported between said cable preferably comprise a plurality of steel encased timbers extending substantially the length and breadth of the drilling structure, each of which is encased in a pair of steel channel members. A plurality of said fenders are disposed parallel to each other both above and below the water line to permit contact by surface vessels in the vicinity of their normal center of gravity.

Further objects and -advantages of the present invention will become apparent from the following detailed description taken in conjunction with the accompanying drawing which forms an integral part of the present specilication.

Fig. l is a side elevation view illustrating a preferred embodiment of the present invention as applied to an oishore drilling structure of the elevated deck drill barge type.

Fig. 2 is an elevation view taken in the direction of arrows 2--2 in Fig. l illustrating, in detail, the cable and fender means and their cooperation with the drilling structure.

Fig. 3 is a cross-sectional view through one of the fender or bumper means taken in the direction of arrows 3-3 in Fig. 2 and particularly illustrates a preferred manner of construction of the fender and the preferred means for clamping said fender to the cable means.

Referring now to the `drawing and, in particular, to Fig. 1, the preferred manner of carrying out the present invention is illustrated as being applied to a drilling structure of the type known in the art as an elevated deck drill barge, identified generally as 10. In this type of drilling structure, drilling platform 11 is supported by a plurality of tubular columns 13, a iixed distance above a submergible barge 12 which is normally floated to position and then submerged into engagement with the underwater bottom. In the arrangement of Fig. l, pontoon members, identified as 14, are utilized in maintaining stability of the barge during the lowering and raising thereof, and are adapted to be extended and retracted by hydraulic operators which utilize the columns 13 directly thercabove as hydraulic cylinders. Drilling, of course, proceeds, as indicated schematically, by means of drill derrick 15, illustrated as being supported on the drilling deck 11..

As indicated by the surface vessel 16, drilling supplies and personnel are transported to and from the drill barge 10 at regular intervals and, of course, it is necessary for surface vessels, such as boat 16, to approach the barge close enough to permit transfer of materials and personnel. As indicated hereinabove, the danger of impact between vessel 16 and any of the columns '13 is a serious hazard both to the drilling operations being performed ing columns.

ance with the present' invention an effective fender sysrearsteel plate 28 Vdescribed hereinabove.

thereon and the ship, 'but mere serious is the 'danger of` damage to the drill platform by impact with the support- Accordingly, there is provided in accordtern forprotectingfthejsupporting columns from such damaging impact which includes a novel combination of steel -cable means, identified as Y17. As shown, cable means 17- extend vertically from a depth below the normal y'centervof. gravity of the surface vessels to a position substantially above the Water line. Y

Asv more particularly shown in Fig. 2, the laterally spacedl plurality of cables 17 are `each pivotally connected through `a cable connector 18 and a pivot pin 19 to the top; 'of bargehull 12. As best seen in Fig. 1, these lat- Veifally spaced vertical cable means are arranged; atspaced p allyl service the platformbut preferably surround bage`12. VEach cable'is arranged to ,be cir-fawn, taut by the sleeve clamps 21 which connectthe upper end: of the cables to Vthe elevated drilling deck 11. n'llirougl'l the cable tensioning byclamp means 21, the degree or extent of'tautnessiof the cables may be` suitably predetermined. This predeterminable extent of tautness will, ofcourse, vary with the size and type of `steel cable. With astandand hard core cable, a greater degree of pretensioning has been found desirable. as compared to the degree of tautness required for bridge strand cables which have a greater degree of twist in theiroriginal spinning.

gAs further illustrated in the drawing, the impact of sur- Yface vessels, such as ship 16, is desirably transmitted to the spaced plurality of cable means 17 by plurality of bumper or fender elements, identified as 24. In the present embodiment, three individual fender elements, or bumpers, extend transversely to the cables and are supported thereon in the vicinity of the water line. As furervals around the periphery of the barge ywhere ships 1 ther shown, at least one of said fenders iskpositioned "slightly above the water line and parallel to another fender located a short distance below the water line. A third fender is supported by cable 17 substantially along the water line.

`In Fig. 3 there is illustrated a preferred manner of constr uctiug fenders, .or bumpers 24. `As there shown, the e'ore of the elongated bumper is preferably constructed of timbensuch as loak beam 26. Timber 26 is desirably clamped between a pair of steel channel members 27, welded together by a pair of elongated plates 28, which serve to enclose'the beam. The combination of oal timbefl 2 6` encased lin steel by channels 27 and plates A28, in the manner illustrated, yields a particularly desirable Shock absorbing structure of relatively light weight and high impact resistance, so that only -a portion o f the shockof vessels contacting the fender is transferred to cables 17; As further shown in Fig. 3, fender means 24. are desirably attached to cable means y17 through a pair of Vhigh degree of protection for the supporting columns 113 is provided by the fender cable assembly illustrated and Particularly, such` columns are protected against damage during adverse weather conditions, when the approach. of surface vessels has been extremely hazardous both to the drilling structure and the ship. v The protective system ofthe present invention hasthe additional advantage of being portable with the drilling structure, so that it may be assembled on the drilling barge and then transported from location to location, with minimum interference to navigation of the drilling barge.

It will, of course, be apparent that the vertically disposed cable means, laterally displaced from the support columns for a drilling platform, may be readily adapted to any otherV type of offshore drilling structure of the portable` or'iixed type, whether suchstructure is supported on bottom by a pontoon or raft foundation, as illustrated in the preferred embodiment, or the structure supported by a plurality of columns or VcaissonsV directly engaging the underwater bottom; In" the latter type of structure, arm members extending outwardly from 'the lower ends of the caissons, provide thel desired anchoring for the lower ends of cables 1 7. plurality of such vertically hung cables will, ofcourse, surround the circumference of the platform and support column system or each caisson will be surrounded.. Fender members interconnecting at least two or more cables-are secured thereto in manner similar to that described above.

It will be understood that various modifications and changes in the foregoing structure may be made without departing from the linvention and all such modifications and Vchanges falling within theA scope of the appended claimkare intended to beincluded therein.

I claim; l n

In a fender system for an o'ishore structure, in combination a platform supported; above the surface of a body of water by a support structure lwhich extends from said platform downwardly throughsad body of water, a plurality of Vvertically disposed laterallyY spaced-apart cables, a respective connector means aiXedto one end of each of said cables,y av respective complementary connector means foreach of said cables afiixed to said support structure in laterally spaced-apartv relationship, means connector means ailixed' to said support structuren separate respective adjustable clamping means for each of said cables affixed to said Vplatform in v laterally spacedapart relationship and clamping'respect'ively yeach of said .cables thereto, said clamping means comprislngm means for adjusting the tension ofthe respective cable clamped thereby, a plurality of bumper elements positioned transversely across said cables in vertically spaced-'apart relationship, means adjustably securing 'each of said' bumper elements to at least two of saidv ables, the latter 'said means compjriSng asplit sleeve substantially surrounding a respective cable at the p o" "n of a said` bumper element, Vand a clamping. means 'd t0 Seid bmt'ler lment and clamping said split sleeve to its respective cable.

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539,447 Germany Nov; 26,1931 

